Get a paper clip or very small screw driver. Stick it in the center hole. It should come out. Hope this helps.

Forgive me... That doesn't help at all.

I've got a small screwdriver that fits in. I've done everything with it that I think I could do with a paper clip. I've pressed pretty hard in the center and tried to pull it out. I've tried screwing it several directions. Pressing it different directions... no dice.

What am I trying to release? Should I be pushing it one way or another?